1. Field of the Invention
The present invention relates to a circuit structure (including an electric circuit structure and an optical circuit structure), a manufacturing method thereof, and a wiring structure.
2. Description of the Background Art
A wiring substrate (or an electric circuit board) having a plurality of wirings and a waveguide substrate (or an optical circuit board) having a plurality of waveguides are used in many fields. Circuit boards such as wiring substrate and waveguide substrate has a circuit structure formed thereon, which has a plurality of conductive paths (i.e., wirings or waveguides) having a prescribed shape and capable of transmitting electricity or light therethrough. A method for manufacturing the circuit structure will now be described in connection with a wiring substrate.
An electrically conductive film (e.g., a metal film) is formed on a substrate and then patterned into a prescribed shape by a photolithography process or the like. The substrate having wirings of a prescribed pattern thereon is thus produced. Alternatively, an electrically conductive layer having a prescribed pattern (i.e., wirings) may be formed on the substrate by a printing method or a transfer method.
In order to form a multi-layer wiring structure, the step of sequentially forming a wiring of a first layer, an insulating layer, and a wiring of a second layer is repeatedly conducted. Every method requires the step of patterning the wiring of each layer into a prescribed shape. More specifically, when the photolithography process is used, the photolithography step must be conducted for every electrically conductive layer for forming the wiring of the respective layer. When the printing method or the transfer method is used, the printing step using a printing plate according to the wiring of each layer or the step of transferring an electrically conductive layer having the same pattern as that of the wiring of each layer is required.
As described above, in order to form a circuit structure having a conductive path in a plurality of layers (such as a multi-layer wiring structure) by the conventional manufacturing method, the step of patterning a conductive path into a prescribed shape is required for every layer. This complicates the manufacturing process, causing increased manufacturing costs and reduced productivity.
The present invention is made to solve the above problems, and it is an object of the present invention to provide a circuit structure manufactured by a method that is simpler than the conventional example, and a manufacturing method thereof.
According to one aspect of the present invention, a circuit structure includes: a plurality of conductive paths each capable of transmitting light or electricity therethrough; a plurality of conductive path layers each having at least one of the plurality of conductive paths; at least one interlayer isolating layer formed between the plurality of conductive path layers; and a plurality of input/output (I/O) sections each connected to any one of the plurality of conductive paths. Each of the plurality of conductive path layers has a first laminated structure that includes a plurality of first conductive layers and at least one first isolating layer formed between the plurality of first conductive layers. The at least one interlayer isolating layer has a second laminated structure that includes a plurality of second isolating layers and at least one second conductive layer formed between the plurality of second isolating layers. The above object is thus achieved.
For example, the circuit structure may function as a waveguide structure. In this case, the plurality of conductive paths are a plurality of waveguides, the plurality of conductive path layers are a plurality of waveguide layers, the plurality of first conductive layers are a plurality of first core layers, and the at least one first isolating layer is at least one first cladding layer. Moreover, the at least one interlayer isolating layer is at least one isolating layer for isolating the waveguide layers from each other, the plurality of second isolating layers are a plurality of second cladding layers, and the plurality of second conductive layers are a plurality of second waveguide layers.
Alternatively, the circuit structure may function as a wiring structure. In this case, the plurality of conductive paths are a plurality of wirings, the plurality of conductive path layers are a plurality of wiring layers, the plurality of first conductive layers are a plurality of first electrically conductive layers, and the at least one first isolating layer is at least one first insulating layer. Moreover, the at least one interlayer isolating layer is at least one interlayer insulating layer, the plurality of second isolating layers are a plurality of second insulating layers, and the plurality of second conductive layers are a plurality of second electrically conductive layers. Furthermore, the plurality of I/O sections are a plurality of input/output (I/O) electrodes.
Each of the plurality of I/O electrodes may contact the plurality of first electrically conductive layers of a corresponding first laminated structure at a surface crossing surfaces of the plurality of first electrically conductive layers.
Preferably, the plurality of first electrically conductive layers included in the first laminated structure and the at least one second electrically conductive layer included in the second laminated structure are formed from substantially the same material, and the at least one first insulating layer included in the first laminated structure and the plurality of second insulating layers included in the second laminated structure are formed from substantially the same material.
Preferably, the above circuit structure further includes a substrate having a plurality of grooves, and the plurality of wiring layers and the at least one interlayer insulating layer are formed in the plurality of grooves.
The first laminated structure and the second laminated structure may be formed from a bilayer membrane of amphiphilic molecules.
Preferably, the first laminated structure and the second laminated structure are formed from a material exhibiting a smectic phase. More preferably, the smectic phase is a smectic E phase.
The first laminated structure and the second laminated structure may include a hardened smectic liquid crystal material.
Preferably, the above circuit structure further includes a substrate having at least one groove, and the first laminated structure is formed in the at least one groove.
According to another aspect of the present invention, a wiring structure includes: a plurality of wiring layers; a plurality of interlayer insulating layers laminated alternately with the plurality of wiring layers; and a plurality of input/output (I/O) electrodes each connected to any one of the plurality of wiring layers. Each of the plurality of wiring layers is not substantially patterned. The above object is thus achieved.
According to still another aspect of the present invention, a method for manufacturing a circuit structure includes the steps of: forming an alternate laminated structure of a plurality of first layers and a plurality of second layers separating the plurality of first layers from each other, the plurality of first layers having a first property, and the plurality of second layers having a second property; and forming a conductive path including at least a part of a first laminated structure, the fist laminated structure forming a part of the alternate laminated structure. The above object is thus achieved.
The above method may further includes the steps of forming another conductive path, the another conductive path being formed from another first laminated structure that forms another part of the alternate laminated structure; and forming an interlayer isolating layer, the interlayer isolating layer being formed from a second laminated structure that forms a part of the alternate laminated structure located between the conductive path and the another conductive path.
Preferably, the above method further includes the step of preparing a substrate having a groove of a prescribed pattern at its surface, and the step of forming the alternate laminated structure includes the step of forming at least a part of the alternate laminated structure within the groove.
The step of preparing the substrate may include the step of forming a plurality of grooves having different depths at the surface of the substrate.
The plurality of first layers may be a plurality of waveguide layers, the plurality of second layers may be a plurality of cladding layers, and the step of forming the conductive path may be the step of forming a waveguide.
Alternatively, the plurality of first layers may be a plurality of electrically conductive layers, the plurality of second layers may be a plurality of insulating layers, and the step of forming the conductive path may be the step of forming a wiring.
Preferably, the step of forming the alternate laminated structure includes the step of forming the alternate laminated structure by using a material exhibiting a smectic phase. More preferably, the smectic phase is a smectic E phase.
The step of forming the alternate laminated structure may include the step of hardening the material exhibiting the smectic phase.